1. Field of the Invention
The present invention relates to a negative-tone resist composition used in microfabrication of a semiconductor device with an electron beam or extreme ultraviolet (EUV) ray, a photoresist compound used for the negative tone resist composition, and, a semiconductor device manufactured by using the negative-tone resist composition.
2. Description of the Related Art
Conventionally, microfabrication by lithography using a photoresist has been performed in a semiconductor manufacturing process. In association with the recent tendency for a higher degree of circuit integration, fine patterns are formed with the size less than 100 nanometers. The wavelength of a beam used for exposure has been decreased from that of a KrF excimer later beam (with a wavelength of 248 nm) to that of an ArF excimer laser beam (with a wavelength of 193 nm), and now the combination of the immersion exposure technique with ArF enables fabrication of 100 nanometers or less. To realize microfabrication of 50 nanometers or less, the lithography technique using the extreme-ultraviolet (EUV) rays (with a wavelength of 13.5 nm) or electron beams are now under development. Now it is required to form various fine patterns including a hole pattern, an isolated line pattern, or a line-and-space, and therefore both positive-tone and negative-tone resist materials are required.
Another important factor is fabrication accuracy in addition to fabrication dimensions. The fabrication accuracy is determined based on the value of line edge roughness. Non-uniformity in pattern dimensions gives influences to performance of semiconductors.
As the negative-tone resist material, the negative-tone resist for Arf described in Japanese Patent Laid-Open Publication NO. 2003-195502 (Patent Document 1) is known. This resist has a hydrophilic γ-hydroxycarboxylic acid structure in a polymer side chain of the acrylic structure. In the exposed portion, esterification occurs in the γ-hydroxycarboxylic acid molecule due to an effect of an acid generated from a photo acid generator, and the hydrophilic characteristic is changed to the hydrophobic one. Therefore, after development using an alkaline developer, the exposed portion becomes insoluble, and a negative-tone pattern is generated.
On the other hand, recently there are also research activities aiming at forming finer patterns using resist based on low-molecular-weight compounds with the size of 1 to 2 nanometers, instead of using polymers with the size of several nanometers or more. A cross-linking type negative-tone resist using calixarene has been reported in Journal of Photopolymer Science and Technology, 2000, 13, p. 413 (Non-Patent Document 1) and Japanese Journal of Applied Physics, 2005, 44, 7B, p. 5581 (Non-Patent Document 2). WO 2004/012012 Publication (Patent Document 2) describes a resist containing a non-polymer molecule as a main component. The resist described in Patent Document 2 provides high resolution and low LER and has four or more reactive sites per molecule, the reactive site being a polarity change reaction moiety.